Fresh flood defence for Notts town (6)

I believe the answer is:

newark

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'notts town' is the definition.
(I've seen this before)

'fresh flood defence' is the wordplay.
'fresh' becomes 'new' (synonyms).
'flood defence' becomes 'ark' (I can't justify this - if you can you should believe this answer much more).
'new'+'ark'='NEWARK'

'for' is the link.

Can you help me to learn more?

(Other definitions for newark that I've seen before include "US airport" , "east coast port" , "Notts. town; NJ city" , "US gateway" , "Town on river Trent where King John died" .)

I've seen this clue in The Times.

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